U.S. national being held in North Korea after crossing border, UN says

The U.S. national crossed the inter-Korean border without authorization, the U.N. Command disclosed.

U.S. national being held in North Korea after crossing border, UN says

North Korea's village of Gijungdong seen from a South Korea's observation post inside the demilitarized zone.

Pool | Getty Images News | Getty Images

A U.S. national may be in North Korean custody after crossing the inter-Korean border without authorization, the U.N. Command said Tuesday on Twitter.

The person was touring the Joint Security Area — a site at Panmunjom in the Demilitarized Zone used by North and South Korea for diplomatic engagements and negotiations. It is bisected by the Military Demarcation Line, also known as the Armistice Line, which demarcates the border between the two territories.

"A U.S. National on a JSA orientation tour crossed, without authorization, the Military Demarcation Line into the Democratic People's Republic of Korea (DPRK). We believe he is currently in DPRK custody and are working with our KPA counterparts to resolve this incident," the United Nations Command said.

The U.N. Command did not disclose the identity or motives of the U.S. national. A U.S. official familiar with the situation told NBC News that the individual is believed to be a U.S. soldier.

A spokesperson for the White House was not immediately available when contacted by NBC News.

Both private companies and the U.N. organize tours of the JSA.

The U.S. and North Korea do not currently have formal diplomatic relations. A U.S. travel advisory note urges U.S. nationals not to travel to North Korea "due to the continuing serious risk of arrest and long-term detention."

The incident takes place on the same day as a U.S. nuclear submarine visited South Korea for the first time since the 1980s, arriving at the port of Busan, according to the U.S. forces in South Korea.